Method and apparatus for reception of control signaling

ABSTRACT

A method and apparatus provide reception of control signaling in a wireless communication network. A first device can communicate with a second device using serving cell operating on an unlicensed carrier. A preamble transmission can be sent to the second device in a first set of at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol starting with a first orthogonal frequency division multiplexing symbol in a subframe sent on the serving cell. The first OFDM symbol can have a first cyclic prefix. A second OFDM symbol can be in the subframe to the second device such that the second OFDM symbol immediately follows the first set of OFDM symbols. Control information can be sent in a second set of OFDM symbols beginning with the second OFDM symbol to the second device. The second set of OFDM symbols can have a second cyclic prefix. The duration of the first cyclic prefix can be larger than the duration of the second cyclic prefix.

BACKGROUND

1. Field

The present disclosure is directed to a method and apparatus forreception of control signaling. More particularly, the presentdisclosure is directed to a method and apparatus for reception ofcontrol signaling at a first wireless communication device from a secondwireless communication device on a wireless network.

2. Introduction

Presently, users use portable devices, otherwise known as User Equipment(UE), such as smartphones, cell phones, tablet computers, selective callreceivers, and other wireless communication devices, on Long TermEvolution (LTE) networks. Users use the UEs to download files, music,e-mail messages, and other data, as well as to watch streaming video,play streaming music, play games, surf the web, and engage in other dataintensive activities. Because of large amounts of downloaded data aswell as large amounts of users, LTE operators can now use unlicensedspectrum to complement the bandwidth of their LTE networks to providefaster data to users. This allows the users to download data faster ontheir portable devices. For example, unlicensed spectrum can includespectrum at 5 GHz (e.g. used by WiFi) and other unlicensed spectrum. LTEtechnology can be deployed in unlicensed spectrum using the carrieraggregation framework where a primary cell uses licensed spectrum, and asecondary cell is deployed in the unlicensed spectrum. Transmissions onthe unlicensed carrier frequency typically have to follow DiscontinuousTransmission requirements (DCT requirements) due to regulatoryrequirements and due the need to co-exist with other wireless systemsoperating in the same spectrum, such as Wi-Fi systems, LTE devices, suchas UE's, and base stations, such as Enhanced Node-B's (eNBs). In someregulations, a LTE device may also be required to performlisten-before-talk (LBT) prior to transmitting on a carrier. If thedevice finds that the channel is busy, then it should defer itstransmission until the carrier become clear.

If a first device, such as a UE is configured with a Scell operating onunlicensed spectrum, in order to receive and decode information fromphysical layer signals and channels from a second device in a particularsubframe on that Scell, the first device may have to take into accountwhether the second device has any transmissions in that subframe; and ifthere are transmissions, whether the transmissions in that subframe aretruncated; and if the transmissions are truncated, the location of thosetransmissions, such as the stating or ending Frequency DivisionMultiplexing (OFDM) symbol of the transmission(s), within that subframe.Unfortunately, present devices do not adequately provide for receptionof control signaling in such a system. Thus, there is a need for amethod and apparatus for improved reception of control signaling in awireless communication network.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of thedisclosure can be obtained, a description of the disclosure is renderedby reference to specific embodiments thereof which are illustrated inthe appended drawings. These drawings depict only example embodiments ofthe disclosure and are not therefore to be considered to be limiting ofits scope.

FIG. 1 is an example block diagram of a system according to a possibleembodiment;

FIG. 2 is an example illustration of subframes including orthogonalfrequency multiplexed symbols with different length cyclic prefixesreceived by a user equipment according to a possible embodiment;

FIG. 3 is an example flowchart illustrating the operation of a wirelesscommunication device according to a possible embodiment;

FIG. 4 is an example flowchart illustrating the operation of a wirelesscommunication device according to a possible embodiment;

FIG. 5 is an example flowchart illustrating the operation of a wirelesscommunication device according to a possible embodiment;

FIG. 6 is an example block diagram of an apparatus according to apossible embodiment; and

FIG. 7 is an example block diagram of a base station according to apossible embodiment.

DETAILED DESCRIPTION

Embodiments can provide for a method and apparatus reception of controlsignaling in a wireless communication network. According to a possibleembodiment, a first device can communicate with a second device using aprimary serving cell (Pcell) operating on a licensed carrier and asecondary serving cell (Scell) operating on an unlicensed carrier. Apreamble transmission can be detected from the second device in a firstset of at least one Orthogonal Frequency Division Multiplexing (OFDM)symbol starting with a first OFDM symbol in a subframe received on theScell. The first OFDM symbol can have a first Cyclic Prefix (CP). Asecond OFDM symbol in the subframe can be determined such that thesecond OFDM symbol immediately follows the first set of OFDM symbols.Downlink Control Information (DCI) containing a Physical Downlink SharedChannel (PDSCH) resource assignment can be decoded in a second set ofOFDM symbols beginning with the second OFDM symbol. The second set ofOFDM symbols can have a second CP. The duration of the first CP can belarger than the duration of the second CP.

According to another possible embodiment, a first set of a first number(k1) of control channel Blind Decoding (BD) candidates can be monitoredby a device in a first subframe at an aggregation level for a controlchannel transmission in the first subframe starting from a first OFDMsymbol position (s1) in the first subframe. A second set of a secondnumber (k2) of control channel BD candidates can be monitored in thefirst subframe at the aggregation level for a control channeltransmission in the first subframe starting from a second OFDM symbol(s2) position in the first subframe. A third set of a third number (k3)of control channel BD candidates can be monitored in a second subframeat the aggregation level for a control channel transmission in thesecond subframe starting only from a first OFDM symbol position (s1) inthe second subframe when a Downlink Control Information (DCI) intendedfor the device is successfully decoded from a candidate in the secondset of the second number (k2) of control channel BD candidates, wherek3>k1 and k3>k2. The first OFDM symbol position (s1) in the firstsubframe can be the same position as the first OFDM symbol position (s1)in the second subframe. In one example, k1=3, k2=3, and k3=6. The valuesfor the control channel blind decoding candidates can also varydepending on the type of control channel (e.g. PDCCH or EPDCCH).

According to another possible embodiment, Downlink Control Information(DCI) containing PDSCH resource assignment(s) can be received in one oftwo types of control channels in a subframe. A type of truncation of thesubframe can be determined based on the type of control channel on whichthe DCI is received. The PDSCH can be decoded based on at least thedetermined type of truncation of the subframe.

FIG. 1 is an example illustration of a system 100 according to apossible embodiment. The system 100 can include a first device 110 and asecond device 120. While the first device 110 is illustrated as a UserEquipment (UE) and the second device 120 is illustrated as a basestation, such as an Enhanced Node-B (eNB), the roles may also bereversed. Furthermore, the devices 110 and 120 can be the same type ofdevice, such as UE's or base stations, and can be any other type ofdevice that can send and receive wireless communication signals. Forillustrative purposes in some embodiments, the first device will bereferred to as a UE and the second device 120 will be referred to as abase station, but it is understood that the first device 110 and thesecond device 120 can be any transmitting and/or receiving devices inall of the embodiments. The first device 110 and the second device 120can communicate on different cells 130 and 140. The cell 130 can be afirst cell, such as a primary serving cell (Pcell) and the first device110 can be connected to the primary cell. The cell 140 can be a secondcell, such as a secondary cell (Scell). The second cell 140 can also bea cell that operates on unlicensed spectrum. The cells 130 and 140 canfurther be cells associated with other base stations, can be a macrocells, can be small cells, can be pico cells, can be micro cells, can befemto cells, and/or can be any other cells useful for operation with aLTE network. The system 100 can also include a another device 112 thatcan communicate with the second device 120 on cells 132 and 142 in asimilar manner to the first device 110. The devices 110 and 112 can beany devices that can access a wireless network. For example, the devices110 and 112 can be UE's, such as wireless terminals, portable wirelesscommunication devices, stationary wireless communication devices,smartphones, cellular telephones, flip phones, personal digitalassistants, personal computers having cellular network access cards,selective call receivers, tablet computers, or any other device that iscapable of operating on a wireless network. In operation, the firstdevice 110 can communicate with the second device 120 using the Pcell130 operating on a licensed carrier and the Scell 140 operating on anunlicensed carrier.

For example, Third Generation Partnership Project (3GPP) LTE Releases10-12 for Carrier Aggregation (CA) or dual connectivity, may allow aneNB to configure an Scell, such as a secondary carrier or a secondaryComponent Carrier (CC), to provide additional frequency resources forcommunication to a UE in addition to a Pcell. A Scell can operate via aCA mechanism, but some of the procedures identified for CA can also bereused for dual connectivity, such as when the Scell and Pcell belong todifferent cell groups.

Due to regulatory requirements, and due the need to co-exist with otherwireless systems, such as Wi-Fi, cordless phones, wireless local areanetworks, and other wireless systems, LTE devices, such as UE's andeNB's, can take different issues into account while operating on anunlicensed carrier. For example, LTE devices typically have to checkwhether the carrier is busy by using some form of Listen Before Talk(LBT) mechanism before transmitting on an unlicensed carrier. A LTEdevice can then begin transmissions only if the carrier is free. LBTtypically includes measuring the energy on the carrier, sometimesreferred to as sensing, for a short duration, such as 9 us or 20 us, anddetermining whether the measured energy is less than a threshold, suchas −82 dBm or −62 dBm. If the energy is less than the threshold, thecarrier is determined to be free. Some examples of LBT include ClearChannel Assessment-Energy Detect (CCA-ED) and Clear ChannelAssessment-Carrier Sense (CCA-CS) mechanisms defined in IEEE 802.11specifications, CCA mechanisms specified in ETSI EN 301 893specification, and other forms of LBT. As another example, transmissionson the carrier typically also have to follow Discontinuous Transmission(DCT) requirements. For example, the LTE device can continuouslytransmit for X ms, such as where X can be 4 for some regulations and upto 13 for other regulations, after which it may have to ceasetransmission for some duration, sometimes referred as idle period,perform LBT again, and reinitiate transmission only if LBT issuccessful. The device may perform LBT towards the end of the idleperiod. Embodiments can provide modifications to transmission andreception of LTE signals and channels to enable efficient operation inunlicensed spectrum. Some embodiments can relate to LTE 3GPP TS 36.211,which is incorporated by reference in its entirety.

In LTE, physical layer signals and channels, such as control channelslike a Physical Downlink Control Channel (PDCCH) and an EnhancedPhysical Downlink Control Channel (EPDCCH); data channels like aPhysical Downlink Shared Channel (PDSCH); and reference andsynchronization signals like a Primary Synchronization Signal (PSS), aSecondary Synchronization Signal (SSS), a Cell-Specific Reference Signal(CRS), a Demodulation Reference Signal (DM-RS) and a Channel StateInformation-Reference Signal (CSI-RS); and discovery signals, aretransmitted on Resource Elements (RE's) of OFDM symbols. For normalCyclic Prefix (CP) operation, the OFDM symbols are of ˜71 us duration.Seven OFDM symbols comprise a 0.5 ms slot and two slots comprise a 1 msLTE subframe. Therefore, a LTE subframe comprises 14 OFDM symbols, suchas symbol 0 to symbol 13 by counting the symbols across both slots.

In LTE Release12 (Rel12) and earlier releases, to receive controlsignaling, the UE monitors a set of PDCCH/EPDCCH candidates. Monitoringimplies attempting to decode each of the candidates according to allapplicable Downlink Control Information (DCI) formats for thatcandidate. The set of PDCCH candidates to monitor are defined in termsof search spaces at different Control Channel Element (CCE) aggregationlevels, where an aggregation level indicates the number of CCEs in theaggregation. Similarly, the set of EPDCCH candidates to monitor aredefined in terms of search spaces at different Enhanced Control ChannelElement (ECCE) aggregation levels. Each CCE consists of multipleResource-Element Groups (REG's) where REG's are used for defining themapping of control channels such as PDCCH to time-frequency resources,such as Resource Elements (RE's), within a subframe. For example, inLTE, one RE corresponds to a single subcarrier mapped in frequencydomain and a single OFDM symbol mapped in time domain and a REG includesmultiple RE's mapped in the frequency domain. Similarly, each ECCEconsists of multiple enhanced Resource-Element Groups (eREG's) whereeREG's are used for defining the mapping of control channels such asEPDCCH to RE's within a subframe.

In LTE Rel12, the UE expects PDCCH to be transmitted in the beginningOFDM symbols in the time domain of a subframe. For example, when thePhysical Control Format Indicator (PCFICH) indicates n=2, the UE expectsPDCCH to be transmitted in the first two OFDM symbols. Given this, theUE maps (or determines the mapping for) the RE's in the beginning OFDMsymbols to REG's and CCE's, and numbers the CCE's from 0, 1, . . .N_CCE−1. The UE then performs Blind Decodes (BD's) on a set of theseCCE's within the superset numbered from 0 to N_CCE−1 to determine if aDCI with the relevant DCI format intended for the UE is transmitted onthem. BD's can be performed either on individual CCE's, or on aggregatedCCE's. For example, one BD can be performed for one CCE when aggregationlevel L=1, one BD can be performed for two consecutive CCE's whenaggregation level L=2, and so on. The set of CCE's can be given (ordetermined) by a search space used by the UE to limit its blind decodingcomplexity. Without a search space, the number of BD's can be large. Forexample, considering a 20 MHz carrier bandwidth, an OFDM symbol can have˜20-28 CCE's, i.e., up to ˜50 CCE's for 2 OFDM symbols. Assuming ˜50CCE's, if the UE has to perform BD's at multiple CCE aggregation levels,such as L=1, 2, 4, 8, and try multiple DCI formats, such as DCI format0/1A and DCI format 2/2a/2b/2c depending on the transmission mode, foreach aggregation level, the UE has to perform close to 200 BD's. Tolimit the complexity, the UE can use a search space to perform BD's ononly a set of candidate CCE's for each aggregation level. For example,for an LTE Rel12 Scell, the UE can monitor 6 candidates at aggregationlevel 1, 6 candidates at aggregation level 2, 2 candidates ataggregation level 4, and 2 candidates at aggregation level 8, which canbe represented in [6,6,2,2] candidates for L=1, 2, 4, 8. Assuming the UElooks for two different DCI formats for each candidate, the total numberof BD's can then be restricted to a maximum of (6+6+2+2)*2=32 BD's. Insummary, for LTE Rel12, for PDCCH monitoring, the UE can performs BD'sto decode DCI intended for the UE, assuming that the PDCCH transmissionstarts at the first OFDM symbol (i.e., the beginning OFDM symbol) ineach subframe where PDCCH is monitored.

In LTE Rel12, if the UE is configured to monitor an EPDCCH in asubframe, it can expect the EPDCCH to be transmitted in one or two setsof frequency domain Physical Resource Blocks (PRB's) calledEPDCCH-PRB-sets within the subframe. Similar to PDCCH monitoring, EPDCCHmonitoring can also involve a UE performing BD's in a search spacecorresponding to a set of ECCE's within the EPDCCH-PRB-sets. To reduceUE complexity, the maximum number of BD's for EPDCCH monitoring can alsobe restricted, such as to 16 BD's per DCI format. Typically, for Scells,the UE can determine the starting OFDM symbol in the time domain forEPDCCH reception within each EPDCCH-PRB-set using higher layer, such asRadio Resource Control (RRC), configuration signaling. In summary, forLTE Rel12, for EPDCCH monitoring, the UE can performs BD's to decode DCIintended for the UE, assuming that the EPDCCH transmission for aparticular EPDCCH-PRB-set starts at a starting OFDM symbol, such as1-epdcch-start, configured by higher layers. For example, for twoEPDCCH-PRB-sets, set1 and set2, the eNB can configure1-epdcch-start-set1 as a 3rd OFDM symbol and 1-epdcch-start-set2 as a4th OFDM symbol. In some cases, the UE may also determine 1-epdcch-startusing a Control Format Indicator (CFI) signaled on the PCFICH in thefirst symbol of the subframe. The same concept of blind decodingsplitting and set configurations can also be applied to the case wherethere are more than two sets of EPDCCH-PRB-sets (e.g three or four).

To enable efficient operation in unlicensed spectrum, an eNB cantruncate the transmission of physical layer signals or channels in somesubframes to less than 14 OFDM symbols, where 14 OFDM symbols cancorrespond to a subframe of 1 ms duration, and the eNB can use thetruncated portions, such as a remaining portion of the subframefollowing truncation of the transmission in the subframe, of thosesubframes to perform LBT or as an idle period.

Truncation can typically be used only after continuous transmission in acertain number of subframes. This can depend on the transmissionactivity of the eNB which in turn can depend on the data arrivalpatterns for various UE's served by the eNB. Given this, the truncatedsubframes may not follow a periodic pattern. Further, which subframesare truncated may also be impacted by the variability of the duration ofthe idle period or LBT observation period due to, for example, randombackoff during LBT procedure when the carrier is detected as occupied.Also, the number of symbols truncated in a given subframe can varydepending on operating parameters chosen by the eNB.

Therefore, from a UE perspective, if the UE is configured with an Scelloperating on a carrier/channel in an unlicensed spectrum, and if theScell is activated for the UE, in order to receive and decodeinformation from physical layer signals and channels in a particularsubframe on that Scell, the UE may have to take into account whether theeNB has any transmissions in that subframe; and if there aretransmissions, whether the transmissions in that subframe are truncated;and if the transmissions are truncated, the location of thosetransmissions, such as the starting or ending OFDM symbol of thetransmission(s), within that subframe. Embodiments can provide varioussignaling methods and UE behavior options that enable the UE to do thiswith reduced complexity.

FIG. 2 is an example illustration of subframes 200 including OFDMsymbols with different length cyclic prefixes received by a UE accordingto a possible embodiment. The UE can be configured with a Scell on anunlicensed carrier, such as a uScell, and the Scell can be activated.Once the Scell is activated, the UE can start attempting to detect ordecode a preamble transmission made by an eNB. A preamble can be atransmission which the UE can use to determine the beginning of atransmission burst. The total number of subframes of the transmissionburst can include the subframe containing the preamble and subsequentsubframes that the eNB will be transmitting continuously immediatelyfollowing the preamble. It can also contain other information. Accordingto a first example (example P1), the preamble transmission can be areference signal transmission, such as a CRS/PSS/SSS/discovery signal,occupying one or more OFDM symbols. According to a second example(example P2), the preamble transmission can be within an OFDM symbolwith some RE's of the OFDM symbol mapped for and/or used/configured forPDCCH and some other RE's of the OFDM symbol mapped for and/orused/configured for reference signals such as CRS. According to a thirdexample (example P3), the preamble transmission can be within an OFDMsymbol with some RE's of the OFDM symbol mapped for and/orused/configured for EPDCCH and some other RE's of the OFDM symbol mappedfor or used/configured for, reference signals such as demodulationreference signals (DMRS). According to a fourth example (example P4),the preamble transmission can be within two or more consecutive OFDMsymbols, a first OFDM symbol or a first set of OFDM symbols containingreference signals, such as CRS/PSS/SSS, followed by a last OFDM symbolwith some RE's of the last OFDM symbol mapped for and/or used/configuredfor PDCCH and some other RE's of the last OFDM symbol mapped for and/orused/configured for reference signals such as CRS. Instead of one lastOFDM symbol, two or more OFDM symbols with some RE's of the last OFDMsymbol mapped for and/or used/configured for PDCCH and some other RE'sof the last OFDM symbol mapped for and/or used/configured for referencesignals such as CRS is also possible. According to a fifth example(example P5), the preamble transmission can be within two or moreconsecutive OFDM symbols, a first OFDM symbol or a first set of OFDMsymbols containing reference signals, such as DMRS/PSS/SSS, followed bya last OFDM symbol with some RE's of the last OFDM symbol mapped forand/or used/configured for EPDCCH and some other RE's of the last OFDMsymbol mapped for and/or used/configured for reference signals such asDMRS. Instead of one last OFDM symbol, two or more OFDM symbols withsome RE's of the last OFDM symbol can be mapped for and/orused/configured for EPDCCH and some other RE's of the last OFDM symbolcan be mapped for and/or used/configured for reference signals, such asDMRS.

The UE may assume a longer Cyclic Prefix (CP) with a duration Tcp1, suchas extended CP duration as defined in LTE specifications, for thebeginning OFDM symbol corresponding to the preamble transmission and ashorter cyclic prefix with duration Tcp2, such as a normal CP durationas defined in LTE specifications, for subsequent symbols in the subframecontaining the preamble and other subsequent subframes. According to apossible embodiment, the UE can detect a preamble transmission from asecond device in a first set of Orthogonal Frequency DivisionMultiplexing (OFDM) symbols starting with a first OFDM symbol in a firstsubframe received on the Scell, the first OFDM symbol having a firstCyclic Prefix (CP). The UE can determine a second OFDM symbol in thefirst subframe such that the second OFDM symbol immediately follows thefirst set of OFDM symbols. The UE can decode Downlink ControlInformation (DCI) containing Physical Downlink Shared Channel (PDSCH)resource assignments in a second set of OFDM symbols beginning with thesecond OFDM symbol, the second set of OFDM symbols having a secondCyclic Prefix (CP). The duration of the first CP can be larger than theduration of the second CP.

An extended CP can mean the OFDM symbol has a CP length of 512 timedomain samples and normal CP can mean the OFDM symbol has a CP length of144 or 160 time domain samples, where each time domain sample can be1/(15000*2048) seconds. Other CP lengths can be used for other systems.The extra time domain transmission in the longer CP, such asdeltacp=Tcp1−Tcp2, can help the UE better tune its hardware, such as forAutomatic Gain Control (AGC) maintenance, for decoding the preamble OFDMsymbol and subsequent symbols. This is illustrated in the subframes 200,which show OFDM symbols of Pcell 210 and uScell 220 of two subframes n230 and n+1 235. In the subframes 200, the UE can attempt todetect/decode a preamble transmission on the Scell in OFDM symbollocations 0, 1, 2, and 3 of subframe n 230 assuming that the OFDM symbolcorresponding to preamble transmission has a larger CP 242 than otherOFDM symbols that have a shorter CP 244. After detecting the preamble inOFDM symbol 240, the UE can assume a shorter CP for subsequent OFDMsymbols in the subframe containing the preamble, such as subframe n 230,and other subsequent subframes, such as subframe n+1 235. This approachcan be especially suitable for the second and third examples above wherethe UE may not assume any prior reference signal transmissionsimmediately preceding the PDCCH/EPDCCH transmission. For the fourth andfifth examples where the preamble transmission can be within two or moreconsecutive OFDM symbols, the first OFDM symbol of the preambletransmission can use a longer CP, while the remaining OFDM symbols ofthe preamble transmission can use a shorter CP.

For the second, third, fourth, and fifth examples, the preamble cancarry Downlink Control Information (DCI) that can provide information,such as preamble information, about the subframe containing the preambleand a set of subsequent subframes immediately following the preamble,sometimes also referred as the portion of transmission burst followingthe preamble. Preamble information can indicate the number of subsequentsubframes that the eNB will be transmitting continuously immediatelyfollowing the preamble. For example, the DCI can have 4 bits indicatingN_TX_BURST, the total number of subframes of the transmission burst,such as the subframe containing the preamble and subsequent subframesthat the eNB will be transmitting continuously immediately following thepreamble. Details about other additional information that the DCI canprovide are given below. The DCI can be Cyclic Redundancy Check (CRC)masked using a special identifier associated with preamble reception,such as a Preamble Radio Network Temporary Identifier (PRE-RNTI). The UEcan be configured by higher layers, such as RRC or Medium Access Control(MAC) layers, with a PRE-RNTI value. The PRE-RNTI value may also bebased on the cell ID or virtual cell ID used for transmission of thecell-specific reference signals or discovery signals for thecorresponding Scell. The DCI can be sent using a compact DCI format suchas DCI Format 1C or DCI Format 1A, or any new payload size(s) definedfor preamble DCI. The preamble DCI may be of multiple different payloadsizes, and a UE may be configured via higher layers with one or multiplepayload sizes to search for.

For the second and fourth examples, in the OFDM symbol where the UEexpects preamble PDCCH transmission, the UE can map the RE's in the OFDMsymbol to REG's, such as 4 REs per REG or 6 RE's per REG, and CCE's,such as 9 REG's per CCE, and number them from 0, 1, . . . NpreCCE−1. TheUE can then perform BD's on a set of these CCE's within the supersetnumbered from 0 to NpreCCE−1 to determine if DCI with the relevant DCIformat containing the preamble information is transmitted on them. BD'scan be performed either on individual CCE's, or on aggregated CCE's. Forexample, a UE can try a maximum of 4 BD's at aggregation level 4, suchas with starting CCE locations 0, 4, 8, 12, and 2 BD's at aggregationlevel 8, such as with starting CCE locations 0, 8. In a second example,the aggregation levels, and/or the number of BD's per aggregation level,etc. may be configured via higher layer signaling.

For the third and fifth examples, in the OFDM symbol where the UEexpects preamble EPDCCH transmission, the UE can map the RE's in theOFDM symbol to eREGs and ECCE's, and number them from 0, 1, . . .NpreECCE−1. The UE can then performs BD's on a set of these ECCEs withinthe superset numbered from 0 to NpreECCE−1 to determine if DCI with therelevant DCI format containing preamble information is transmitted onthem. BD's can be performed either on individual ECCE's or on aggregatedECCE's. For example, a UE can try a maximum of 4 BDs at aggregationlevel 4, such as with starting ECCE location 0, 4, 8, 12, and 2 BD's ataggregation level 8, such as with starting ECCE locations 0, 8. In asecond example, the aggregation levels, and/or the number of BD's peraggregation level, etc. may be configured via higher layer signaling.

In one embodiment, the antenna port(s) on which the reference signal(s)associated with the preamble transmission are transmitted is assumed tobe quasi co-located with antenna port(s) of at least a portion of thereference signals associated with discovery signals transmissions withinthe discovery signal occasion on the Scell. The reference signalsassociated with discovery signals transmissions can comprisecell-specific reference signals on antenna port 0, and non-zero-powerCSI reference signals on CSI-RS antenna ports 15-22. For the second andfourth examples, the CRS reference signal antenna ports (associated withthe preamble transmission) may be assumed to be quasi co-located withcell-specific reference signals on antenna port 0 of the discoverysignal. For the third and fifth examples, the UE may be configured toassume the antenna port(s) on which Demodulation Reference Signal (DMRS)(associated with the preamble transmission) are transmitted is quasico-located with CSI-RS antenna ports of the discovery signals. Anantenna port can be defined such that the channel over which a symbol onthe antenna port is conveyed can be inferred from the channel over whichanother symbol on the same antenna port is conveyed. Two antenna portsare said to be quasi co-located if the large-scale properties of thechannel over which a symbol on one antenna port is conveyed can beinferred from the channel over which a symbol on the other antenna portis conveyed. The large-scale properties can include one or more of delayspread, Doppler spread, Doppler shift, average gain, and average delay.Discovery signals may be transmitted on the Scell to enable the UE toperform Radio Resource Management (RRM) measurements functions.

While attempting to detect/decode the preamble transmission, the UE canassume that the end of the OFDM symbol(s) containing preambletransmission is/are aligned with the end of the OFDM symbol boundarieson Pcell within a small timing error difference, such as +/−31.3 us(micro-seconds) when compared to Pcell. Alternately, the UE maydetermine the end of the OFDM symbol boundary of the preambletransmission by first detecting a discovery signal on the Scell and thenuse that discovery signal to determine symbol timing.

While attempting to detect/decode the preamble transmission, for eachsubframe, the UE may assume that the preamble transmission can onlybegin within a subset of OFDM symbol positions within the subframe. Forexample, the UE can detect a preamble transmission from a second devicein a first set of Orthogonal Frequency Division Multiplexing (OFDM)symbols starting with a first OFDM symbol in a first subframe receivedon the Scell where the first OFDM symbol can have a first Cyclic Prefix(CP). According to a first example, the UE can assume possible preamblestart positions are OFDM symbols 0, 1, 2, 3, 4, 5, 6, such as any symbolin the first slot, in each subframe. According to a second example, theUE can assume possible preamble start positions are OFDM symbols 0, 1,2, 3 in each subframe, which can be suitable for EPDCCH based operation.According to a third example, the UE can assume possible preamble startpositions are OFDM symbols 6, 13 in each subframe, such as the lastsymbol in each slot. According to a fourth example, the UE can assumepossible preamble start positions are OFDM symbols 5, 6, 12, 13 in eachsubframe, such as the last two symbols in each slot. According to afifth example, the UE can assume possible preamble start positions areOFDM symbols 0, 1, 2, 3, 4, 5, 6, 7, such as any symbol in the firstslot and the first symbol in the second slot, in each subframe.According to a sixth example, if the UE is configured to monitor thePDCCH in subframe n for receiving PDSCH resource assignment(s), it canassume preamble start positions are OFDM symbol 13 in subframe n−1, andOFDM symbol 6 in subframe n. If the UE is configured to monitor theEPDCCH in subframe n for receiving PDSCH resource assignments, it canassume preamble start positions are OFDM symbol 13 in subframe n−1, andOFDM symbols 0, 1, 2, 3 in subframe n. According to a seventh example,the UE can assume the preamble can start from any OFDM symbol, such assymbols 0-13, in the subframe. For the first through sixth examples, thesubset can be smaller than all 14 possible starting locations. Theseexamples can help reduce UE preamble detection complexity. In thesubframe n where the UE detects/decodes the preamble, the UE can attemptto decode control channels, such as PDCCH or EPDCCH, for DCI containingresource assignment(s) for PDSCH transmission starting with the firstOFDM symbol immediately following the OFDM symbol where preamble isdetected/decoded or a predetermined OFDM symbol following the OFDMsymbol where preamble is detected/decoded. For example, the UE candetermine a second OFDM symbol in the first subframe such that thesecond OFDM symbol immediately follows the first set of OFDM symbols.For the second, third, fourth, and fifth examples above (i.e., P2, P3,P4, P5), since the UE may have to perform BD's in the preamble OFDMsymbol to decode the DCI that can contain preamble information, in orderto keep the UE BD complexity low, the UE can perform a smaller number ofBD's to decode control channels, such as PDCCH or EPDCCH, for DCIcontaining resource assignments for PDSCH transmission. For example, theUE can use maximum of 13 BD's per DCI format, such as [5,5,2,1] BDcandidates for L=1, 2, 4, 8. According to a possible implementation, theUE can be a first device that can communicate with a second device usinga primary serving cell (Pcell) operating on a licensed carrier and asecondary serving cell (Scell) operating on an unlicensed carrier. Thefirst device can detect a preamble transmission from the second devicein a first set of at least one Orthogonal Frequency DivisionMultiplexing (OFDM) symbol starting with a first OFDM symbol in asubframe received on the Scell. The first OFDM symbol can have a firstCyclic Prefix (CP). The first device can determine a second OFDM symbolin the subframe such that the second OFDM symbol can immediately followthe first set of OFDM symbols. The first device can decode DownlinkControl Information (DCI) containing Physical Downlink Shared Channel(PDSCH) resource assignment in a second set of OFDM symbols beginningwith the second OFDM symbol. The second set of OFDM symbols can have asecond Cyclic Prefix (CP). The duration of the first CP can be largerthan the duration of the second CP.

In subsequent subframes immediately following the subframe in which thepreamble is detected or decoded, the UE can attempt to decode controlchannels, such as PDCCH or EPDCCH, for DCI containing resourceassignments for PDSCH transmission using the same OFDM symbol startingpositions it would for a subframe without truncation. If N_TX_BURST isprovided as part of the DCI containing preamble information as discussedearlier, the UE can do this for N_TX_BURST−1 subframes. Alternatively,N_TX_BURST can be provided to the UE via RRC signaling or throughactivation Medium Access Control layer Control Element (MAC layer CE),or through an activation command received via PDCCH/EPDCCH on Pcell. Tomonitor PDCCH, the UE can assume PDCCH starts with the first OFDMsymbol, such as symbol 0. The UE can a use maximum of 16 BD's per DCIformat, such as [6,6,2,2] BD candidates for L=1, 2, 4, 8. To monitorEPDCCH, the UE can assume that the EPDCCH transmission for a particularEPDCCH-PRB-set starts at a starting OFDM symbol, such as 1-epdcch-start,configured by higher layers or can determine it using PCFICH transmittedin the first OFDM symbol of the subframe. The UE can use a maximum of 16BD's per DCI format for EPDCCH reception across all EPDCCH-PRB-sets.

According to another possible embodiment, a UE can be configured with aScell on an unlicensed carrier, and the Scell can be activated. Once theScell is activated, the UE can start monitoring PDCCH/EPDCCH for DCIproviding resource assignment information to receive PDSCH. According toa first example, in each activated subframe, the UE can try 2 BD's forPDCCH and 2 BD's for each EPDCCH in a EPDCCH-PRB-set with startingsymbols x1, x2, x3, where x1, x2, x3 can be RRC configured. According toa second example, in each activated subframe, the UE can try 4 BD's forPDCCH, 3 BD's for EPDCCH in a EPDCCH-PRB-set with starting symbol x1,and one BD for EPDCCH in a EPDCCH-PRB-set with starting symbol x2, wherex2 can be a large value (e.g. x2>4). In this example, fewer BDs areallocated for starting symbol x2 since it may be difficult to schedulemultiple UE's in only few symbols. According to a third example, in eachactivated subframe, the UE can try 4 BD's for PDCCH and 2 DCI formats;only one DCI format for EPDCCH and 3 BD's for EPDCCH in a EPDCCH-PRB-setwith starting symbols x1, and 3 BD's for EPDCCH in a EPDCCH-PRB-set withstarting symbol x2, and 2 BD's for EPDCCH in a EPDCCH-PRB-set withstarting symbol x3. In this example, DCI Format 1A may only be supportedon PDCCH and not monitored for EPDCCH. According to a fourth example,the UE can try no PDCCH BD's, 2 BD's for EPDCCH with start symbol x1 andend symbol y1, 2 BD's for EPDCCH with start symbol x1 and end symbol y2,2 BD's for EPDCCH with start symbol x2 and end symbol y1, 2 BD's forEPDCCH with start symbol x3 and end symbol y1, where y1=13, x1=0 and x2,y2 are RRC configured, or alternately all positions (x1, y1, x2, y2) areRRC configured. In these examples, to monitor PDCCH, the UE can assumePDCCH transmission starts in OFDM symbol 0 of each monitored subframe.Other examples where the UE assumes PDCCH transmission start either inOFDM symbol 0 or in OFDM symbol 7 of the subframe are also possible.

The UE can use a N_TX_BURST value, which can be provided to it via RRCsignaling, through activation MAC layer CE-medium access control layercontrol element or can be provided through an activation commandreceived via PDCCH/EPDCCH on the Pcell. The N_TX_BURST value canindicate the total number of subframes of a transmission burst, whichcan be the number of subframes that the eNB can continuously transmitbefore discontinuing transmission due to LBT or idle periodrequirements.

If the UE successfully decodes a PDCCH with starting symbol other thanOFDM symbol 0 (i.e., the initial OFDM symbol in the subframe), or if theUE successfully decodes an EPDCCH with starting symbol greater than OFDMsymbol 3, the UE can determine that the front-portion of this subframeis truncated. The UE can also determine that the next N_TX_BURST-1subframes will not be truncated in the front-portion. UE can use thisknowledge to reassign its BD's for the next N_TX_BURST−1 subframes.

For example, the UE can initially monitor the PDCCH assuming a PDCCHtransmission starts either in OFDM symbol 0 or in OFDM symbol 7. If theUE successfully decodes a PDCCH with starting symbol other than OFDMsymbol 0 in subframe n, then from subframe n+1 to n+N_TX_BURST−1, the UEcan monitor PDCCH by assuming PDCCH transmission starts only in OFDMsymbol 0. In this example, for subframe n, the UE can perform k1 BD's,such as for k1=3, for aggregation level L1, such as with L1=2, byassuming PDCCH transmission starts in OFDM symbol 0, and can performs k2BD's, such as for k2=3, for the same aggregation level L1 by assumingPDCCH transmission starts in OFDM symbol 7. However, for subframes n+1to n+N_TX_BURST−1, for the same aggregation level L1, the UE can performk3=k1+k2, such as k3=6, BD's by assuming the PDCCH transmission startsonly in OFDM symbol 0, where k3>k1.

As another example, the UE can initially monitor EPDCCH assuming EPDCCHtransmission in a particular EPDCCH-PRB-set starts either in OFDM symbolx1 or in OFDM symbol x2, where x1<=3 and x2>3. If the UE successfullydecodes an EPDCCH with starting OFDM symbol x2 in subframe n, fromsubframe n+1 to n+N_TX_BURST−1, the UE can monitor EPDCCH by assumingthe EPDCCH transmission starts only in OFDM symbol x1. In this example,for subframe n, the UE can perform k1 BD's, such as for k1=3, foraggregation level L1, such as for L1=2, by assuming EPDCCH transmissionstarts in OFDM symbol x1, and can perform k2 BD's, such as for k2=3, forthe same aggregation level L1 by assuming EPDCCH transmission starts inOFDM symbol x2. However, for subframes n+1 to n+N_TX_BURST−1, for thesame aggregation level L1, the UE can perform k3=k1+k2, such as k3=6,BD's assuming EPDCCH transmission starts only in OFDM symbol x1, wherek3>k1.

According to a possible implementation of this embodiment, a UE canmonitor in a first subframe, a first set of a first number (k1) ofcontrol channel Blind Decoding (BD) candidates at an aggregation levelfor a control channel transmission in the first subframe starting from afirst OFDM symbol position (s1) in the first subframe. The UE canmonitor in the first subframe, a second set of a second number (k2) ofcontrol channel BD candidates at the aggregation level for a controlchannel transmission in the first subframe starting from a second OFDMsymbol (s2) position in the first subframe. The UE can determine DCIintended for the device is successfully decoded from a candidate in thesecond set. The UE can then monitor in a second subframe, a third set ofa third number (k3) of control channel BD candidates (where k3>k1 andk3>k2) at the aggregation level for a control channel transmission inthe second subframe starting only from a first OFDM symbol position (s1)in the second subframe when DCI intended for the device is successfullydecoded from a candidate in the second set of the second number (k2) ofcontrol channel BD candidates. The first OFDM symbol position (s1) inthe first subframe can be the same position as the first OFDM symbolposition (s1) in the second subframe.

While embodiments described above are explained in the context ofunlicensed Scells, the methods can also be used for UE/eNB operation ona Scell operating on a licensed carrier, and some of the methods canalso be used for UE/eNB operation on a Pcell.

As far as information transmitted in a preamble, as discussed above, apreamble can provide information about an LTE transmission burst on anunlicensed carrier. The preamble can be carried on the unlicensedcarrier at the beginning of the burst, for example, and a preamble sentin OFDM symbols x through y, where x can be a value from 1 to 14(assuming, for this example, the beginning OFDM symbol in the subframeis OFDM symbol 1, and last OFDM symbol in the subframe is OFDM symbol14) and y can be a value from 1 to 14, may indicate to the UE one ormore of different parameters. In other implementations, x and y can be avalue from 0 to 13. For example, a preamble can indicate the eNBtransmission burst duration. A preamble sent in OFDM symbols x through ycan also indicate subframes that are configured downlink subframes inthe burst and possibly the subframe configuration. A preamble sent inOFDM symbols x through y can also indicate subframes that are configuredas uplink subframes in the burst and possibly the subframeconfiguration. A preamble sent in OFDM symbols x through y can alsoindicate subframes that are configured as special subframes, such aswith truncation and type of truncation, such as front truncation or backtruncation or both front and back-truncations, in the burst. A preamblesent in OFDM symbols x through y can also indicate presence/absence ofcontrol channels and/or control channel configuration, such as searchspace details, number of blind decodes per control channel type, etc.,in each subframe of a burst, where there may be multiple control channelconfigurations depending on how the eNB may desire to perform LBT. Apreamble sent in OFDM symbols x through y can also indicate thepresence/absence of certain reference signals and/or configuration ofthe reference signals, such as CRS, PSS, SSS, DRS, etc., in subframes ofthe burst. A preamble sent in OFDM symbols x through y can also indicatethe presence/absence of and/or configuration of Multimedia BroadcastMulticast Service (MBMS) transmissions in the burst. A preamble sent inOFDM symbols x through y can also indicate the presence/absence ofand/or configuration of Positioning Reference Symbols (PRS) in theburst. A preamble sent in OFDM symbols x through y can also indicate aconfiguration of the uplink signals/channels, such as whether SoundingReference Signal (SRS) is configured or not configured. A preamble sentin OFDM symbols x through y can also indicateforward-compatibility/release-signaling/blank subframe signaling. Apreamble sent in OFDM symbols x through y can also indicate LBTconfiguration information, such as for coordination with neighboringnodes.

Instead of signaling the above parameters in a preamble on an unlicensedcarrier, one or more of the above parameters may be signaled to the UEvia a licensed carrier that is configured to the UE, such as in a commonor UE-specific search space on the primary or a secondary cell. Thisinformation can sent using a DCI format 1C similar to EnhancedInterference Mitigation and Traffic Adaptation (EIMTA) signaling or DCIformat 1A associated with the unlicensed carrier. The transmission burstduration may be the duration for which the base station transmits thedownlink signal or the duration for which the base station intends totransmit the downlink signals. In some cases, the base station may ceasetransmission before its transmission burst duration, such as when it hasno data to transmit. Signalling of the the transmission burst durationmay be the indicator to the UE of when the UE can restart looking forthe preamble from the eNB.

Typically, a UE may be configured to detect a preamble associated withits serving cell on the unlicensed carrier. However, the UE may alsodetect or be configured to detect a preamble associated with one or moreadjacent cells on the unlicensed carrier. If the UE can detect apreamble from the adjacent cell, it may be able to use that informationas assistance information for improving its performance. It may also beable to use that information to enhance in-device co-existence, such asif the UE detects a transmission burst from an eNB, the UE may be ableto adapt the WiFi LBT operation in the UE based on the LTE transmissionburst.

Neighboring eNBs may be able to listen to over-the-air transmissions ofthe preamble from the eNB to adapt their LTE transmission/reception.Typically for a single operator scenario, there may be fiberconnectivity between eNBs of a single operator, which may not requireover-the-air inter-eNB communication, but, for multi-operator scenarios,over-the-air reception of the preambles may provide some benefit forcoordination.

An eNB can indicate via higher layers if it allows front truncation only(truncation during the beginning OFDM symbol(s) of a subframe), backtruncation only (truncation during the ending OFDM symbol(s) of asubframe), or both front and back-truncations. For configuration oftypes of truncation, if an eNB indicates that front truncation is notconfigured, then the UE can assume that any subframe used for LTEtransmission has at least CRS present in the first one or two OFDMsymbols. If an eNB indicates that front truncation is configured and UEdetects EPDCCH in a subframe, then the UE can assume that the subframedoes not have CRS present in the first one or two OFDM symbols. If thecorresponding DCI in the EPDCCH indicates a PDSCH starting symbol thatis earlier, such as OFDM symbol 0, for transmission modes 1-8 or TM1-8,then the UE can assume CRS is present in the first one or two OFDMsymbols. If an eNB indicates that front truncation is configured and UEdetects PDCCH in a subframe, then the UE can assume that the subframehas CRS present in the first one or two OFDM symbols.

Typically, both PDCCH and EPDCCH can be used as control channels onunlicensed carriers. Depending on the amount of flexibility required,such as when control can start at any arbitrary OFDM symbol relative toLTE subframe timing, the respective control channel designs can beenhanced. PDCCH, may have better coverage/performance than distributedEPDCCH, and can be of short transmission duration, such as 1-4 OFDMsymbols, which can be more suitable when last symbols of a subframe aretruncated for CCA. However, changes can be made if first symbols of asubframe may have to be truncated, such as using different startingpositions. For PDCCH, the best alternative location can be the first 2-3symbols of second slot, assuming that CRS can be present only in legacyRE locations. EPDCCH can work without changes if first 2 or 3 symbols ina subframe are always set aside, such as for LBT operation, and it mayneed changes if the last symbols of a subframe need to be truncated forLBT. It can be feasible to operate with EPDCCH only. With differentstart and end symbols, new DMRS patterns may be required. CRS-baseddemodulation can also be used for EPDCCH. More EPDCCH sets, e.g. >2, orfor each set, more than one start and end symbols can be configured.

A UE can be configured to detect/decode both EPDCCH and PDCCH. Thedetection may be done in the same subframe or a time-divisionmultiplexing fashion at subframe level. For example, the UE can attemptto detect EPDCCH in a first set of subframes, and can attempt to decodePDCCH in a second set of subframes, where the first and second sets donot overlap. For UE-specific search space, the UE may attempt to decodePDCCH/PCFICH as in Rel12, and it may also attempt to decode EPDCCH withone or multiple starting positions. If UE decodes PDCCH, then thedetected DCI on the PDCCH can inform the UE of the number of symbolstruncated at end for PDSCH. If UE decodes EPDCCH, the same startingsymbol as EPDCCH can be assumed for PDSCH and no truncation assumed atend of subframe.

Typically both front and back truncation may be required. The truncationvalue for PDSCH can be indicated via the control channel. For instance,in DCI transmitted on PDCCH, the field may indicate end-truncationvalue, while for DCI transmitted on the EPDCCH, the field may indicatethe front-truncation value. Therefore, UE can receive downlink controlinformation in one of two types of control channels, can interpret asubframe truncation field in the received DCI based on the type ofcontrol channel on which the DCI is received, and can attempt to decodedata based on the interpreted subframe truncation field values and otherinformation in the DCI. Here, the truncation can be a front truncationin a subframe if the DCI is received in the PDCCH, and the truncationcan be a back truncation in a subframe if DCI is received in the EPDCCH.For example, the UE can receive Downlink Control Information (DCI)containing PDSCH resource assignment(s) in one of two types of controlchannels in a subframe. The UE can determine a type of truncation of thesubframe based on the type of control channel on which the DCI isreceived. The UE can decode the PDSCH based on at least the determinedtype of truncation of the subframe.

If a UE has to blindly detect whether a subframe is back-truncated orfront-truncated, then the UE can be configured to blindly detect somePDCCH candidates to detect back-truncation and some EPDCCH candidates todetect front-truncation in that subframe. Another alternative can be touse an indicator that dynamically indicates to the UE which hypothesesthe UE should perform in a given subframe or set of subframes. Forinstance, a 1-bit indicator can be signaled on the Pcell or as part ofan initial signal transmission on an unlicensed carrier to indicatewhich control channels the UE should monitor in a given subframe. If inmost subframes, there may be no truncation, then more blind decodes canbe allocated to a control channel that begins earlier in the subframethan to a control channel that begins later in the subframe. Forexample, PDCCH BD's can be more than the EPDCCH BD's. In anotherexample, an EPDCCH set with starting symbol 0 may have more BD's thananother EPDCCH set with starting symbol 3. Therefore, for EPDCCH, BD'scan be split for different sets based on an EPDCCH starting symbolvalue. The aggregation levels can be configurable per control channel orEPDCCH sets. More EPDCCH sets can be defined to allow variable startingsymbols, or more starting symbols can be hypothesized for the sameEPDCCH set.

For a UE configured in TM10 and configured with at least PDCCH-basedcontrol channels, the UE may assume that CRS is present only in thefirst 1 or 2 OFDM symbols in the subframe. This can reduce overhead dueto CRS. This can be equivalent to stating that each subframe may beassumed be a Multicast-Broadcast Single-Frequency Network (MBSFN)subframe, except perhaps the subframes configured for discovery signaltransmission. For UE configured in TM10 and configured with onlyEPDCCH-based control channels, the UE may assume that CRS is present innone of the symbols in the subframe. This can reduce overhead due toCRS, and can be equivalent to stating that each subframe can be assumedto be a new type of subframe, such as a blank subframe, except thesubframes configured for discovery signal transmission, where some CRSmay be present as part of discovery signal.

FIG. 3 is an example flowchart 300 illustrating the operation of awireless communication device, such as the first device 110, accordingto a possible embodiment. At 310, the flowchart 300 can begin. At 320,the device can communicate with a second device, such as the seconddevice 120, using a primary serving cell (Pcell) operating on a licensedcarrier and a secondary serving cell (Scell) operating on an unlicensedcarrier.

At 330, a preamble transmission from the second device can be detectedin a first set of Orthogonal Frequency Division Multiplexing (OFDM)symbols starting with a first OFDM symbol in a subframe received on theScell. The first OFDM symbol can have a first Cyclic Prefix (CP). Apreamble can be a transmission which the wireless communication devicecan use to determine the beginning of a transmission burst. Whendetecting the preamble transmission, the wireless communication devicecan also decode the preamble transmission. The first set of at least oneOFDM symbol can be only the first OFDM symbol. For example, the preamblecan be one or two OFDM symbols. At least one RE of the first OFDM symbolcan be mapped for at least one of the following signals: a PrimarySynchronization Signal (PSS), a Secondary Synchronization Signal (SSS),a Cell-specific Reference Signal (CRS), a Discovery Signal, a ChannelState Information-Reference Signal (CSI-RS), and a wirelesscommunication device-specific reference signal. The preambletransmission can be within the first OFDM symbol with a first set ofResource Elements (RE's) of the first OFDM symbol configured for aPhysical Downlink Control Channel (PDCCH) and a second set of RE's ofthe first OFDM symbol mapped for reference signals. For example, theother RE's of the first OFDM symbol can be mapped for reference signals,such as Cell Specific Reference Signals (CRS's). A first set of RE's ofthe first OFDM symbol can be mapped for an Enhanced PDCCH (EPDCCH) and asecond set of RE's of the first OFDM symbol are mapped for referencesignals. For example, the other RE's of the first OFDM symbol (i.e., thesecond set of RE's) can be mapped for reference signals, such asDemodulation Reference Signals (DMRS's). The first and second set ofRE's may typically not overlap.

Detecting the preamble transmission can include hypothesizing that thepreamble transmission begins within a subset of OFDM symbol positionswithin the subframe. The wireless communication device can do blinddetection to determine the location of the preamble transmission. An endof the first OFDM symbol can be aligned with an end of OFDM symbolboundaries on the Pcell within a timing error difference. For example,the given error difference can be a small timing error difference, suchas +/−31.3 us.

The preamble transmission can carry preamble information indicating anumber of subsequent subframes that the second device intends totransmit continuously immediately following the first subframe. Thesubframe can be a first subframe and the preamble information can have 4bits indicating a total number of subframes of a transmission burstincluding the first subframe and subsequent subframes the second devicetransmits continuously immediately following the first subframe. Forexample, the 4 bits can indicate N_TX_BURST as the total number ofsubframes of the transmission burst. The preamble information can beencoded with a Cyclic Redundancy Check (CRC) parity code and the CRCparity bits can be masked using a special identifier associated withpreamble reception. For example, the special identifier can be aPreamble Radio Network Temporary Identifier (PRE-RNTI). The specialidentifier can be a cell ID or a virtual cell ID associated with theScell and which can be indicated to the wireless communication device aspart of RRC/MAC configuration message. Detecting the preambletransmission can include decoding a downlink control information (DCI)containing preamble information in the first subframe by monitoring amaximum of a first number (N1) of control channel blind decodingcandidates. For example, a maximum of N1 control channel blind decodingcandidates can be monitored, where N1=N14+N18, and N14 and N18 can be anumber of control channel blind decoding candidates corresponding toCCE/ECCE aggregation level 4 and 8 respectively, and where N14=4 andN18=2. Detecting the preamble transmission can include successfullydecoding downlink control information (DCI) containing preambleinformation.

Detecting a preamble transmission from the second device in a first setof at least one Orthogonal Frequency Division Multiplexing (OFDM) symbolstarting with a first OFDM symbol in a subframe received on the Scell,the first OFDM symbol having a first Cyclic Prefix (CP) can be anotherway of saying detecting a preamble transmission from the second devicein a first set of Orthogonal Frequency Division Multiplexing (OFDM)symbols starting with a first OFDM symbol in a subframe received on theScell by assuming that a first cyclic prefix value is used for the firstOFDM symbol. For example, by “assuming,” the wireless communicationdevice can detect the preamble by using hypotheses for first and secondCP values.

At 340, a second OFDM symbol can be determined in the subframe such thatthe second OFDM symbol immediately follows the first set of OFDMsymbols.

At 350, Downlink Control Information (DCI) containing Physical DownlinkShared Channel (PDSCH) resource assignment can be decoded in a secondset of OFDM symbols beginning with the second OFDM symbol in the firstsubframe, the second set of OFDM symbols having a second Cyclic Prefix(CP). The DCI can be decoded by monitoring a maximum of a second number(N2) of control channel blind decoding candidates. For example, amaximum of N2 control channel blind decoding candidates can bemonitored, where N2=N21+N22+N24+N28 and where N21, N22, N24, and N28 canbe a number of control channel blind decoding candidates correspondingto CCE/ECCE aggregation levels 1, 2, 4, and 8 respectively. The durationof the first CP can be larger than the duration of the second CP. Forexample, the first CP can be an extended CP and the second CP can be anormal CP. As a further example, extended CP can mean the OFDM symbolhas a CP length of 512 time domain samples and normal CP can mean theOFDM symbol has a CP length of 144 or 160 time domain samples, whereeach time domain sample can be 1/(15000*2048) seconds. The DCIcontaining preamble information can also be decoded as part of thepreamble detection at 330. Decoding Downlink Control Information (DCI)containing Physical Downlink Shared Channel (PDSCH) resource assignmentin a second set of OFDM symbols beginning with the second OFDM symbol,the second set of OFDM symbols having a second Cyclic Prefix (CP) can beanother way of saying decoding Downlink Control Information (DCI)containing Physical Downlink Shared Channel (PDSCH) resource assignmentin a second set of OFDM symbols beginning with the second OFDM symbol byassuming a second cyclic prefix value is used for the second set of OFDMsymbols.

At 360, DCI containing PDSCH resource assignment can be decoded in asecond subframe immediately following the first subframe by monitoring amaximum of a third number (N3) of control channel blind decodingcandidates where the third number (N3) can be greater than the secondnumber (N2). For example, a maximum of N3 control channel blind decodingcandidates can be monitored where N3 can be greater than N2, whereN3=N31+N32+N34+N38 and where N31, N32, N34, and N38 can be a number ofcontrol channel blind decoding candidates corresponding to CCE/ECCEaggregation levels 1, 2, 4, and 8 respectively. At 370, the flowchart300 can end.

FIG. 4 is an example flowchart 400 illustrating the operation of awireless communication device, such as the first device 110, accordingto a possible embodiment. The operations of the flowchart 400 and theother flowcharts can be performed on a Scell, on a Pcell, on acombination of a Scell and a Pcell, or on any other cell. At 410, theflowchart 400 can begin. At 420, the wireless communication device cancommunicate with a second device using a primary serving cell (Pcell)operating on a licensed carrier and a secondary serving cell (Scell)operating on an unlicensed carrier. The operations of the flowchart 400and the other flowcharts can also be performed completely on a Scell, ona Pcell, on a combination of a Scell and a Pcell, or on any other cellor combinations of cells.

At 430, a transmission burst value can be received via higher layersthan a physical layer. The transmission burst value can indicate anumber of subframes of a transmission burst received before a continuoustransmission of the subframes is discontinued. For example, the devicecan receive a N_TX_BURST value that can be provided to it via RRCsignaling, can be provided through activation Medium Access Controllayer Control Element (MAC layer CE), can be provided through anactivation command received via PDCCH/EPDCCH on a Pcell. The value canbe provided to the device from another device, such as a base station orany other device that can provide a transmission burst value.

At 440, a first set of a first number (k1) of control channel BlindDecoding (BD) candidates can be monitored in a first subframe at anaggregation level for a control channel transmission in the firstsubframe starting from a first OFDM symbol position (s1) in the firstsubframe. Monitoring can mean attempting to decode. At 450, a second setof a second number (k2) of control channel BD candidates can bemonitored in the first subframe at the aggregation level for a controlchannel transmission in the first subframe starting from a second OFDMsymbol (s2) position in the first subframe. The first OFDM symbolposition (s1) in the first subframe can be the same position as thefirst OFDM symbol position (s1) in the second subframe.

According to a possible embodiment, the control channel can be a PDCCHand the control channel BD candidates can be PDCCH BD candidates.According to a possible implementation, the first OFDM symbol positioncan be the initial OFDM symbol in the subframe and the second OFDMsymbol position can be an OFDM symbol whose position can be an integernumber of OFDM symbols later than the initial OFDM symbol in thesubframe. According to another possible implementation, the first OFDMsymbol position can be the initial OFDM symbol in the subframe and thesecond OFDM symbol position can be an OFDM symbol whose position can beseven OFDM symbols later than the initial OFDM symbol in the subframe.For example, the second OFDM symbol can be the eighth symbol in thesubframe. In an instance where the first symbol is labeled with a zero(0), the second OFDM symbol as the eighth symbol can be labeled with aseven (7).

According to another possible embodiment, the control channel can anEPDCCH and the control channel BD candidates can be EPDCCH BD candidateswithin a first set of frequency domain resource blocks (RBs) configuredby layers higher than a physical layer. According to a possibleimplementation, the first OFDM symbol position can be the initial OFDMsymbol in the subframe and the second OFDM symbol position can be anOFDM symbol whose position can be an integer number of OFDM symbolslater than the initial OFDM symbol in the subframe. According to anotherpossible implementation, the first OFDM symbol position can be theinitial OFDM symbol in the subframe and the second OFDM symbol positioncan be an OFDM symbol whose position can be four OFDM symbols later thanthe initial OFDM symbol in the subframe. For example, the second OFDMsymbol can be the fifth symbol in the subframe. In an instance where thefirst symbol is labeled with a zero (0), the second OFDM symbol as thefifth symbol can be labeled with a four (4).

At 460, a third set of a third number (k3) of control channel BDcandidates can be monitored in a second subframe at the aggregationlevel for a control channel transmission in the second subframe startingonly from a first OFDM symbol position (s1) in the second subframe whena Downlink Control Information (DCI) intended for the device issuccessfully decoded from a candidate in the second set of the secondnumber (k2) of control channel BD candidates, where k3>k1 and k3>k2. Thethird number (k3) of control channel BD candidates can be equal to thefirst number (k1) of control channel BD candidates plus the secondnumber (k2) of control channel BD candidates (k3=k1+k2). Monitoring inthe second subframe can be performed when the second subframe can bewithin a total number of subframes of a transmission burst from thefirst subframe.

The terms “first OFDM symbol” and “second OFDM symbol” are used todistinguish the symbols from each other and they are not necessarily thefirst and the second absolute symbols in the subframe unless otherwiseindicated. Similarly, the terms “first OFDM symbol position” and “secondOFDM symbol position” are used to distinguish the symbols from eachother and they are not necessarily the first and the second absolutesymbol positions in the subframe unless otherwise indicated.

At 470, a second DCI containing a Physical Downlink Shared Channel(PDSCH) resource assignment can be decoded in at least one candidate inthe third set of the third number (k3) of control channel BD candidates.

For example, a device can monitor, in a first subframe, a first set of afirst number (k1) of control channel Blind Decoding (BD) candidates atan aggregation level assuming that the control channel transmission inthe first subframe starts from a first OFDM symbol position (s1) in thefirst subframe. Then the device can monitor, in the first subframe, asecond set of a second number (k2) of control channel BD candidates atthe aggregation level assuming that the control channel transmission inthe first subframe starts from a second OFDM symbol (s2) position in thefirst subframe. Then the device can determine DCI intended for thedevice is successfully decoded from a candidate in the second set. Thenthe device can monitor in a second subframe, a third set of a thirdnumber (k3) of control channel BD candidates (where k3>k1 and k3>k2) atthe aggregation level assuming that the control channel transmission inthe second subframe starts only from a first OFDM symbol position (s1)in the second subframe when DCI intended for the device is successfullydecoded from a candidate in the second set of the second number (k2) ofcontrol channel BD candidates. The first OFDM symbol position (s1) inthe first subframe can be the same position as the first OFDM symbolposition (s1) in the second subframe. At 480, the flowchart 400 can end.

FIG. 5 is an example flowchart 500 illustrating the operation of awireless communication device, such as the first device 110, accordingto a possible embodiment. At 510, the flowchart 500 can begin. At 520,the wireless communication device can communicate with a second deviceusing a primary serving cell (Pcell) operating on a licensed carrier anda secondary serving cell (Scell) operating on an unlicensed carrier. At530, Downlink Control Information (DCI) containing PDSCH resourceassignments can be received in one of two types of control channels in asubframe. At 540, a type of truncation of the subframe can be determinedbased on the type of control channel on which the DCI is received.

At 550, the PDSCH can be decoded based on at least the determined typeof truncation of the subframe. Decoding can also mean the device caneither decode the PDSCH based on the DCI, or the device can do someprocessing (e.g. compute rate, SINR, etc) to make a determination if itis worth decoding the PDSCH (i.e. if it is likely the decoding willresult in failure of the packet) and skip decoding the PDSCH to savesome decoding complexity. The DCI can include a subframe truncationfield indicating a truncation value for receiving PDSCH in the subframeand decoding can include decoding the PDSCH based on at least thedetermined type of truncation of the subframe and the truncation value.For example, a DCI can be received in two different types of controlchannel (PDCCH and EPDCCH). There can be a truncation field in the DCI.The field can be interpreted by the device in two or more differentways. Which of the interpretation to use can be discerned by the devicebased on the control channel in which the field was received. Accordingto a possible implementation, the truncation value can be a number ofOFDM symbols in the truncated portion of the subframe. According toanother related implementation, the number of OFDM symbols can be thenumber of symbols by which the subframe is truncated. Decoding can alsoinclude decoding the PDSCH based on the determined type of truncation ofthe subframe and other information included in the DCI. For example, theother information can include a PDSCH resource assignment and otherinformation.

According to a possible embodiment, determining at 540 can includeascertaining that the truncation is a back truncation in the subframe ifthe DCI is received in a PDCCH and at 560, downlink channel quality canbe estimated based on reference signals in at least one of the beginningtwo OFDM symbols in the subframe when the truncation is a backtruncation. Reference signals can be Common Reference Signals (CRS).According to another possible embodiment, determining at 540 can includeascertaining that the truncation is a front truncation in the subframeif DCI is received in an EPDCCH and at 560 downlink channel quality canbe estimated based on reference signals present in OFDM symbols otherthan at least one of the first two OFDM symbols of the subframe when thetruncation is a front truncation. Reference signals can be CRS orChannel State Information Reference Signals (CSI-RS). According toanother possible embodiment receiving 530, determining 540, and decoding550 can be performed on the Scell. At 570, the flowchart 500 can end.

It should be understood that, notwithstanding the particular steps asshown in the figures, a variety of additional or different steps can beperformed depending upon the embodiment, and one or more of theparticular steps can be rearranged, repeated or eliminated entirelydepending upon the embodiment. Also, some of the steps performed can berepeated on an ongoing or continuous basis simultaneously while othersteps are performed. Furthermore, different steps can be performed bydifferent elements or in a single element of the disclosed embodiments.

FIG. 6 is an example block diagram of an apparatus 600, such as thefirst device 110 or the other device 112, according to a possibleembodiment. The apparatus 600 can include a housing 610, a controller620 within the housing 610, audio input and output circuitry 630 coupledto the controller 620, a display 640 coupled to the controller 620, atransceiver 650 coupled to the controller 620, an antenna 655 coupled tothe transceiver 650, a user interface 660 coupled to the controller 620,a memory 670 coupled to the controller 620, and a network interface 680coupled to the controller 620. The elements of the apparatus 600 canperform the UE and apparatus methods described in the disclosedembodiments.

The display 640 can be a viewfinder, a liquid crystal display (LCD), alight emitting diode (LED) display, a plasma display, a projectiondisplay, a touch screen, or any other device that displays information.The transceiver 650 can include a transmitter and/or a receiver. Theaudio input and output circuitry 630 can include a microphone, aspeaker, a transducer, or any other audio input and output circuitry.The user interface 660 can include a keypad, a keyboard, buttons, atouch pad, a joystick, a touch screen display, another additionaldisplay, or any other device useful for providing an interface between auser and an electronic device. The network interface 680 can be auniversal serial bus port, an Ethernet port, an infraredtransmitter/receiver, a USB port, an IEEE 1696 port, a WLAN transceiver,or any other interface that can connect an apparatus to a network orcomputer and that can transmit and receive data communication signals.The memory 670 can include a random access memory, a read only memory,an optical memory, a flash memory, a removable memory, a hard drive, acache, or any other memory that can be coupled to a wirelesscommunication device.

The apparatus 600 and/or the controller 620 may implement any operatingsystem, such as Microsoft Windows®, UNIX®, or LINUX®, Android™, or anyother operating system. Apparatus operation software may be written inany programming language, such as C, C++, Java or Visual Basic, forexample. Apparatus software may also run on an application framework,such as, for example, a Java® framework, a .NET® framework, or any otherapplication framework. The software and/or the operating system may bestored in the memory 670 or elsewhere on the apparatus 600. Theapparatus 600 and/or the controller 620 may also use hardware toimplement disclosed operations. For example, the controller 620 may beany programmable processor. Disclosed embodiments may also beimplemented on a general-purpose or a special purpose computer, aprogrammed microprocessor or microprocessor, peripheral integratedcircuit elements, an application-specific integrated circuit or otherintegrated circuits, hardware/electronic logic circuits, such as adiscrete element circuit, a programmable logic device, such as aprogrammable logic array, field programmable gate-array, or the like. Ingeneral, the controller 620 may be any controller or processor device ordevices capable of operating an electronic device and implementing thedisclosed embodiments.

In operation according to a possible embodiment, the transceiver 650 cancommunicate with a second apparatus using a primary serving cell (Pcell)operating on a licensed carrier and a secondary serving cell (Scell)operating on an unlicensed carrier. The controller 620 can detect apreamble transmission from the second apparatus in a first set of atleast one Orthogonal Frequency Division Multiplexing (OFDM) symbolstarting with a first OFDM symbol in a subframe received on the Scell,the first OFDM symbol having a first Cyclic Prefix (CP). The controller620 can detect the preamble transmission by hypothesizing that thepreamble transmission begins within a subset of OFDM symbol positionswithin the subframe. An end of the first OFDM symbol can be aligned withan end of OFDM symbol boundaries on the Pcell within a timing errordifference.

The controller 620 can determine a second OFDM symbol in the subframesuch that the second OFDM symbol immediately follows the first set ofOFDM symbols. The controller 620 can decode Downlink Control Information(DCI) containing Physical Downlink Shared Channel (PDSCH) resourceassignment in a second set of OFDM symbols beginning with the secondOFDM symbol, the second set of OFDM symbols having a second CyclicPrefix (CP). The duration of the first CP can be larger than theduration of the second CP. For example, the first CP can be an extendedCP and the second CP can be a normal CP.

According to a possible implementation, the first set of at least oneOFDM symbol can be only the first OFDM symbol. The preamble transmissioncan be within the first OFDM symbol with a first set of ResourceElements (RE's) of the first OFDM symbol configured for a PhysicalDownlink Control Channel (PDCCH) and a second set of RE's of the firstOFDM symbol mapped for reference signals. A first set of RE's of thefirst OFDM symbol can be mapped for an Enhanced PDCCH (EPDCCH) and asecond set of RE's of the first OFDM symbol can be mapped for referencesignals. At least one RE of the first OFDM symbol can be mapped for atleast one of the following signals: a Primary Synchronization Signal(PSS), a Secondary Synchronization Signal (SSS), a Cell-specificReference Signal (CRS), a Discovery Signal, a Channel StateInformation-Reference Signal (CSI-RS), and/or an apparatus-specificreference signal.

According to another possible implementation, the subframe can be afirst subframe. The preamble transmission can carry preamble informationindicating a number of subsequent subframes that the second apparatusintends to transmit continuously immediately following the firstsubframe. The preamble information can have 4 bits indicating a totalnumber of subframes of a transmission burst including the first subframeand subsequent subframes the second apparatus transmits continuouslyimmediately following the first subframe. The preamble information canbe encoded with a Cyclic Redundancy Check (CRC) parity code and the CRCparity bits are masked using a special identifier associated withpreamble reception. The controller 620 can detect the preambletransmission by decoding downlink control information (DCI) containingpreamble information in the first subframe by monitoring a maximum of afirst number (N1) of control channel blind decoding candidates. Thecontroller 620 can decode DCI containing at least one PDSCH resourceassignment in the first subframe by monitoring a maximum of a secondnumber (N2) of control channel blind decoding candidates. The controller620 can decode DCI containing PDSCH resource assignment in a secondsubframe immediately following the first subframe by monitoring amaximum of a third number (N3) of control channel blind decodingcandidates where the third number (N3) is greater than the second number(N2). The controller 620 can detect the preamble transmission bysuccessfully decoding downlink control information (DCI) containingpreamble information.

According to another possible embodiment, the transceiver 650 cancommunicate with a second apparatus, such as a base station, anotherdevice, or any other apparatus. For example, the transceiver 650 cancommunicate with a base station using a primary serving cell (Pcell)operating on a licensed carrier and a secondary serving cell (Scell)operating on an unlicensed carrier.

The controller 620 can monitor a first set of a first number (k1) ofcontrol channel Blind Decoding (BD) candidates in a first subframe at anaggregation level for a control channel transmission in the firstsubframe starting from a first OFDM symbol position (s1) in the firstsubframe. Monitoring can include attempting to decode and can beperformed on the Scell or any other cell. The controller 620 can alsomonitor a second set of a second number (k2) of control channel BDcandidates in the first subframe at the aggregation level for a controlchannel transmission in the first subframe starting from a second OFDMsymbol (s2) position in the first subframe.

The controller 620 can monitor a third set of a third number (k3) ofcontrol channel BD candidates (where k3>k1 and k3>k2) in a secondsubframe at the aggregation level for a control channel transmission inthe second subframe starting only from a first OFDM symbol position (s1)in the second subframe when a Downlink Control Information (DCI)intended for the device is successfully decoded from a candidate in thesecond set of the second number (k2) of control channel BD candidates.The first OFDM symbol position (s1) in the first subframe can be thesame position as the first OFDM symbol position (s1) in the secondsubframe.

The DCI can be a first DCI. The controller 620 can successfully decode asecond DCI containing a Physical Downlink Shared Channel (PDSCH)resource assignment in at least one candidate in the third set of thethird number (k3) of control channel BD candidates. The third number ofcontrol channel BD candidates can be equal to the first number ofcontrol channel BD candidates plus the second number of control channelBD candidates (k3=k1+k2).

According to a possible embodiment, monitoring can be performed in thesecond subframe when the second subframe is within a total number ofsubframes of a transmission burst from the first subframe. Thecontroller 620 can receive a transmission burst value via higher layersthan a physical layer. The transmission burst value can indicate anumber of subframes of the transmission burst received before thetransmission of the subframes is discontinued.

According to another related embodiment, the control channel can be aPDCCH and the control channel BD candidates can be PDCCH BD candidates.According to a possible implementation, the first OFDM symbol positioncan be the initial OFDM symbol in the subframe and second OFDM symbolposition can be an OFDM symbol whose position is an integer number ofOFDM symbols later than the initial OFDM symbol in the subframe.According to another possible implementation, the first OFDM symbolposition comprises the initial OFDM symbol in the subframe and thesecond OFDM symbol position comprises an OFDM symbol whose position isseven OFDM symbols later than the initial OFDM symbol in the subframe.

According to another related embodiment, the control channel can be anEPDCCH and the control channel BD candidates can be EPDCCH BD candidateswithin a first set of frequency domain resource blocks (RBs) configuredby layers higher than a physical layer. According to a possibleimplementation, the first OFDM symbol position can be the initial OFDMsymbol in the subframe and the second OFDM symbol position can be anOFDM symbol whose position is an integer number of OFDM symbols laterthan the initial OFDM symbol in the subframe. According to anotherpossible implementation, the first OFDM symbol position can be theinitial OFDM symbol in the subframe and the second OFDM symbol positioncan be an OFDM symbol whose position is four OFDM symbols later than theinitial OFDM symbol in the subframe.

According to another possible embodiment, the transceiver 650 canreceive Downlink Control Information (DCI) containing PDSCH resourceassignments in one of two types of control channels in a subframe. Thecontroller 620 can determine a type of truncation of the subframe basedon the type of control channel on which the DCI is received andconfigured to decode the PDSCH based on at least the determined type oftruncation of the subframe. The controller 620 can decode the PDSCHbased on the determined type of truncation of the subframe and otherinformation included in the DCI. Receiving, determining, and decodingcan be performed on a Scell or any other cell.

According to a possible implementation the transceiver 650 can receive asubframe truncation field in the DCI. The subframe truncation field canindicate a truncation value for receiving PDSCH in the subframe. Thecontroller 620 can then decode the PDSCH based on at least thedetermined type of truncation of the subframe and the truncation value.

According to a possible implementation, the controller 620 can determinethe type of truncation by ascertaining that the truncation is a backtruncation in the subframe if the DCI is received in a PDCCH. Thecontroller 620 can then estimate a downlink channel quality based onreference signals in at least one of the beginning two OFDM symbols inthe subframe.

According to a related implementation, the controller 620 can determinethe type of truncation by ascertaining that the truncation is a fronttruncation in the subframe if DCI is received in an EPDCCH. Thecontroller 620 can then estimate a downlink channel quality based onreference signals present in OFDM symbols other than at least one of thefirst two OFDM symbols of the subframe.

FIG. 7 is an example block diagram of a base station 700, such as theeNB 120, according to a possible embodiment. The base station 700 mayinclude a controller 710, a memory 720, a database interface 730, atransceiver 740, Input/Output (I/O) device interface 750, a networkinterface 760, and a bus 770. The base station 700 can implement anyoperating system, such as Microsoft Windows®, UNIX, or LINUX, forexample. Base station operation software may be written in anyprogramming language, such as C, C++, Java or Visual Basic, for example.The base station software can run on an application framework, such as,for example, a Java® server, a .NET® framework, or any other applicationframework.

The transceiver 740 can create a data connection with the first device110. The controller 710 can be any programmable processor. Disclosedembodiments can also be implemented on a general-purpose or a specialpurpose computer, a programmed microprocessor or microprocessor,peripheral integrated circuit elements, an application-specificintegrated circuit or other integrated circuits, hardware/electroniclogic circuits, such as a discrete element circuit, a programmable logicdevice, such as a programmable logic array, field programmablegate-array, or the like. In general, the controller 710 can be anycontroller or processor device or devices capable of operating a basestation and implementing the disclosed embodiments.

The memory 720 can include volatile and nonvolatile data storage,including one or more electrical, magnetic, or optical memories, such asa Random Access Memory (RAM), cache, hard drive, or other memory device.The memory 720 can have a cache to speed access to specific data. Thememory 720 can also be connected to a Compact Disc-Read Only Memory(CD-ROM), Digital Video Disc-Read Only memory (DVD-ROM), DVD read writeinput, tape drive, thumb drive, or other removable memory device thatallows media content to be directly uploaded into a system. Data can bestored in the memory 720 or in a separate database. For example, thedatabase interface 730 can be used by the controller 710 to access thedatabase. The database can contain any formatting data to connect theterminal 110 to the network 130.

The I/O device interface 750 can be connected to one or more input andoutput devices that may include a keyboard, a mouse, a touch screen, amonitor, a microphone, a voice-recognition device, a speaker, a printer,a disk drive, or any other device or combination of devices that acceptinput and/or provide output. The I/O device interface 750 can receive adata task or connection criteria from a network administrator. Thenetwork connection interface 760 can be connected to a communicationdevice, modem, network interface card, a transceiver, or any otherdevice capable of transmitting and receiving signals to and from thenetwork 130. The components of the base station 700 can be connected viathe bus 770, may be linked wirelessly, or may be otherwise connected.The elements of the base station 700 can perform the second device,second apparatus, and/or base station operations of the disclosedembodiments.

Embodiments can provide for a method of a UE communicating with a basestation using a Pcell operating on a licensed carrier and a Scelloperating on an unlicensed carrier. The method can includedetecting/decoding a preamble transmission in a first set of OFDMsymbols starting with a first OFDM symbol in a first subframe receivedon the Scell by assuming that the first OFDM symbol uses an extended CP.The method can include determining a second OFDM symbol in the firstsubframe such that the second OFDM symbol immediately follows the firstset of OFDM symbols. The method can include decoding DCI containingPDSCH resource assignments, in a second set of OFDM symbols beginningwith the second OFDM symbol by assuming that the second set of OFDMsymbols use a normal prefix.

The preamble transmission can be within the first OFDM symbol (i.e., thefirst set of OFDM symbols has only one symbol) with some RE's of thefirst OFDM symbol mapped for PDCCH and some other RE's of the first OFDMsymbol mapped for reference signals such as CRS. The preambletransmission can be within the first OFDM symbol (i.e., the first set ofOFDM symbols has only one symbol) with some RE's of the first OFDMsymbol mapped for EPDCCH and some other RE's of the first OFDM symbolmapped for reference signals such as DMRS. While attempting todetect/decode the preamble transmission, the UE may assume that thepreamble transmission can only begin within a subset of OFDM symbolpositions within the first subframe. While attempting to detect/decodethe preamble transmission, the UE can assume that the end of the firstOFDM symbol is aligned with the end of the OFDM symbol boundaries onPcell within a small timing error difference (e.g. +/−31.3 us)

The preamble transmission can carry DCI containing information, such aspreamble information, indicating the number of subsequent subframes thatthe base station will be transmitting continuously, immediatelyfollowing the first subframe. The DCI containing preamble informationcan have 4 bits indicating N_TX_BURST, the total number of subframes ofthe transmission burst (i.e., the first subframe containing the preambleand subsequent subframes that the eNB will be transmitting continuouslyimmediately following the first subframe). The DCI containing preambleinformation can be CRC masked using a special identifier (e.g. aPRE-RNTI). To decode decoding DCI containing preamble information in thefirst subframe, the UE can monitor a maximum of N1 control channel blinddecoding candidates. For example, N1=N14+N18, and N14 and N18 are thenumber of control channel blind decoding candidates corresponding toCCE/ECCE aggregation level 4, 8 respectively. To decode DCI containingPDSCH resource assignments in the first subframe, the UE can monitor amaximum of N2 control channel blind decoding candidates. For example,N2=N21+N24+N24+N28, where N21, N22, N24, and N28 can be the number ofcontrol channel blind decoding candidates corresponding to CCE/ECCEaggregation levels 1, 2, 4, 8 respectively. To decode DCI containingPDSCH resource assignments in a second subframe immediately followingthe first subframe, the UE can monitor a maximum of N3 control channelblind decoding candidates where N3 can be greater than N2. For example,N3=N31+N34+N34+N38, where N31, N32, N34, N38 can be the number ofcontrol channel blind decoding candidates corresponding to CCE/ECCEaggregation levels 1, 2, 4, and 8 respectively.

Embodiments can also provide a method in a UE to decode DCI containingPDSCH resource assignments where the UE monitors in a first subframe, afirst set of k1 control channel blind decoding (BD) candidates ataggregation level L1 assuming that the control channel transmissionstarts from OFDM symbol s1 and monitors in the first subframe, a secondset of k2 control channel BD candidates at aggregation level L1 assumingthe that control channel transmission starts from OFDM symbol s2. If DCIintended for the UE is successfully decoded form a candidate in thesecond set, the UE can monitor in a second subframe, a third set of k3control channel BD candidates (where k3>k1) at aggregation level L1assuming the that control channel transmission starts only from OFDMsymbol s1. The UE can do this as long as the second subframe is withinN_TX_BURST−1 subframes from the first subframe. The control channel canbe PDCCH and control channel BD candidates can be PDCCH BD candidates.The control channel can be EPDCCH and control channel BD candidates canbe EPDCCH BD candidates within a EPDCCH-PRB-set.

Embodiments can additionally provide a method where a UE can receive DCIcontaining PDSCH resource assignments in one of two types of controlchannels, can interpret a subframe truncation field in the received DCIbased on the type of control channel on which the DCI is received, andattempt to decode data based on the interpreted subframe truncationfield values and other information in the DCI. The UE can interpret thatthe truncation is a front truncation in a subframe if the DCI isreceived in the PDCCH, and the truncation is a back truncation in asubframe if DCI is received in the EPDCCH.

Although not required, embodiments can be implemented usingcomputer-executable instructions, such as program modules, beingexecuted by an electronic device, such as a general purpose computer.Generally, program modules can include routine programs, objects,components, data structures, and other program modules that performparticular tasks or implement particular abstract data types. Theprogram modules may be software-based and/or may be hardware-based. Forexample, the program modules may be stored on computer readable storagemedia, such as hardware discs, flash drives, optical drives, solid statedrives, CD-ROM media, thumb drives, and other computer readable storagemedia that provide non-transitory storage aside from a transitorypropagating signal. Moreover, embodiments may be practiced in networkcomputing environments with many types of computer systemconfigurations, including personal computers, hand-held devices,multi-processor systems, microprocessor-based or programmable consumerelectronics, network personal computers, minicomputers, mainframecomputers, and other computing environments.

The method of this disclosure can be implemented on a programmedprocessor. However, the controllers, flowcharts, and modules may also beimplemented on a general purpose or special purpose computer, aprogrammed microprocessor or microcontroller and peripheral integratedcircuit elements, an integrated circuit, a hardware electronic or logiccircuit such as a discrete element circuit, a programmable logic device,or the like. In general, any device on which resides a finite statemachine capable of implementing the flowcharts shown in the figures maybe used to implement the processor functions of this disclosure.

While this disclosure has been described with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. For example,various components of the embodiments may be interchanged, added, orsubstituted in the other embodiments. Also, all of the elements of eachfigure are not necessary for operation of the disclosed embodiments. Forexample, one of ordinary skill in the art of the disclosed embodimentswould be enabled to make and use the teachings of the disclosure bysimply employing the elements of the independent claims. Accordingly,embodiments of the disclosure as set forth herein are intended to beillustrative, not limiting. Various changes may be made withoutdeparting from the spirit and scope of the disclosure.

In this document, relational terms such as “first,” “second,” and thelike may be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. The phrase“at least one of” followed by a list is defined to mean one, some, orall, but not necessarily all of, the elements in the list. The terms“comprises,” “comprising,” or any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus. An elementproceeded by “a,” “an,” or the like does not, without more constraints,preclude the existence of additional identical elements in the process,method, article, or apparatus that comprises the element. Also, the term“another” is defined as at least a second or more. The terms“including,” “having,” and the like, as used herein, are defined as“comprising.” Furthermore, the background section is written as theinventor's own understanding of the context of some embodiments at thetime of filing and includes the inventor's own recognition of anyproblems with existing technologies and/or problems experienced in theinventor's own work.

We claim:
 1. A method in a first device, the method comprising:communicating with a second device using serving cell operating on anunlicensed carrier; sending a preamble transmission to the second devicein a first set of at least one orthogonal frequency divisionmultiplexing symbol starting with a first orthogonal frequency divisionmultiplexing symbol in a subframe sent on the serving cell, the firstorthogonal frequency division multiplexing symbol having a first cyclicprefix; sending a second orthogonal frequency division multiplexingsymbol in the subframe to the second device such that the secondorthogonal frequency division multiplexing symbol immediately followsthe first set of orthogonal frequency division multiplexing symbols; andsending control information in a second set of orthogonal frequencydivision multiplexing symbols beginning with the second orthogonalfrequency division multiplexing symbol to the second device, the secondset of orthogonal frequency division multiplexing symbols having asecond cyclic prefix, wherein the duration of the first cyclic prefix islarger than the duration of the second cyclic prefix.
 2. The methodaccording to claim 1, wherein sending control information furthercomprises sending downlink control information containing physicaldownlink shared channel resource assignment.
 3. The method according toclaim 1, wherein the first set of at least one orthogonal frequencydivision multiplexing symbol comprises only the first orthogonalfrequency division multiplexing symbol.
 4. The method according to claim3, wherein the preamble transmission is within the first orthogonalfrequency division multiplexing symbol with a first set of resourceelements of the first orthogonal frequency division multiplexing symbolconfigured for a physical downlink control channel and a second set ofresource elements of the first orthogonal frequency divisionmultiplexing symbol mapped for reference signals.
 5. The methodaccording to claim 3, wherein a first set of resource elements of thefirst orthogonal frequency division multiplexing symbol are mapped foran enhanced physical downlink control channel and a second set ofresource elements of the first orthogonal frequency divisionmultiplexing symbol are mapped for reference signals.
 6. The methodaccording to claim 1, wherein the serving cell comprises a secondaryserving cell, wherein the second device also communicates using aprimary serving cell operating on a licensed carrier, and wherein an endof the first orthogonal frequency division multiplexing symbol isaligned with an end of orthogonal frequency division multiplexing symbolboundaries on the primary serving cell within a timing error difference.7. The method according to claim 1, wherein the preamble transmissioncarries preamble information indicating a number of subsequent subframesthat the first device intends to transmit continuously immediatelyfollowing the subframe.
 8. The method according to claim 7, wherein thesubframe comprises a first subframe, and wherein the preambleinformation has four bits indicating a total number of subframesincluding the first subframe and subsequent subframes the first devicetransmits continuously immediately following the first subframe.
 9. Themethod according to claim 7, wherein the preamble information is encodedwith a cyclic redundancy check parity code and the cyclic redundancycheck parity bits are masked using a special identifier associated withpreamble reception.
 10. The method according to claim 7, wherein sendingthe preamble transmission includes sending downlink control informationcontaining preamble information in the first subframe by monitoring amaximum of a first number of control channel blind decoding candidates.11. The method according to claim 3, wherein at least one resourceelement of the first orthogonal frequency division multiplexing symbolis mapped for at least one of the following signals: a primarysynchronization signal, a secondary synchronization signal, acell-specific reference signal, a discovery signal, a channel stateinformation-reference signal, and a first device-specific referencesignal.
 12. The method according to claim 1, wherein the first cyclicprefix is an extended cyclic prefix and the second cyclic prefix is anormal cyclic prefix.
 13. The method according to claim 1, wherein thefirst device is a base station and the second device is a userequipment.
 14. An apparatus comprising: a transceiver that communicateswith a second apparatus using a serving cell operating on an unlicensedcarrier; and a controller coupled to the transceiver, where thecontroller generates a preamble transmission in a first set of at leastone orthogonal frequency division multiplexing symbol starting with afirst orthogonal frequency division multiplexing symbol in a subframetransmitted on the serving cell, the first orthogonal frequency divisionmultiplexing symbol having a first cyclic prefix, wherein thetransceiver sends the preamble transmission to the second apparatus,sends a second orthogonal frequency division multiplexing symbol in thesubframe to the second apparatus such that the second orthogonalfrequency division multiplexing symbol immediately follows the first setof orthogonal frequency division multiplexing symbols, and sends controlinformation in a second set of orthogonal frequency divisionmultiplexing symbols beginning with the second orthogonal frequencydivision multiplexing symbol to the second apparatus, the second set oforthogonal frequency division multiplexing symbols having a secondcyclic prefix, and wherein the duration of the first cyclic prefix islarger than the duration of the second cyclic prefix.
 15. The apparatusaccording to claim 14, wherein sending control information includessending downlink control information containing physical downlink sharedchannel resource assignment.
 16. The apparatus according to claim 14,wherein the first set of at least one orthogonal frequency divisionmultiplexing symbol comprises only the first orthogonal frequencydivision multiplexing symbol.
 17. The apparatus according to claim 16,wherein the preamble transmission is within the first orthogonalfrequency division multiplexing symbol with a first set of resourceelements of the first orthogonal frequency division multiplexing symbolconfigured for a physical downlink control channel and a second set ofresource elements of the first orthogonal frequency divisionmultiplexing symbol mapped for reference signals.
 18. The apparatusaccording to claim 16, wherein a first set of resource elements of thefirst orthogonal frequency division multiplexing symbol are mapped foran enhanced physical downlink control channel and a second set ofresource elements of the first orthogonal frequency divisionmultiplexing symbol are mapped for reference signals.
 19. The apparatusaccording to claim 14, wherein the serving cell comprises a secondaryserving cell, wherein the second device also communicates using aprimary serving cell operating on a licensed carrier, and wherein an endof the first orthogonal frequency division multiplexing symbol isaligned with an end of orthogonal frequency division multiplexing symbolboundaries on the primary serving cell within a timing error difference.20. The apparatus according to claim 14, wherein the subframe comprisesa first subframe, and wherein the preamble transmission carries preambleinformation indicating a number of subsequent subframes that theapparatus intends to transmit continuously immediately following thefirst subframe.
 21. The apparatus according to claim 20, wherein thepreamble information has four bits indicating a total number ofsubframes of a transmission burst including the first subframe andsubsequent subframes the apparatus transmits continuously immediatelyfollowing the first subframe.
 22. The apparatus according to claim 20,wherein the preamble information is encoded with a cyclic redundancycheck parity code and the cyclic redundancy check parity bits are maskedusing a special identifier associated with preamble reception.
 23. Theapparatus according to claim 16, wherein at least one resource elementof the first orthogonal frequency division multiplexing symbol is mappedfor at least one of the following signals: a primary synchronizationsignal, a secondary synchronization signal, a cell-specific referencesignal, a discovery signal, a channel state information-referencesignal, and an apparatus-specific reference signal.
 24. The apparatusaccording to claim 14, wherein the first cyclic prefix is an extendedcyclic prefix and the second cyclic prefix is a normal cyclic prefix.25. The apparatus according to claim 14, wherein the apparatus is a basestation and the second apparatus is a user equipment.